/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.db.mpp.execution.operator.process;

import com.google.common.util.concurrent.ListenableFuture;
import org.apache.iotdb.db.mpp.execution.operator.Operator;
import org.apache.iotdb.db.mpp.execution.operator.OperatorContext;
import org.apache.iotdb.db.mpp.execution.operator.process.fill.IFill;
import org.apache.iotdb.tsfile.read.common.block.TsBlock;
import org.apache.iotdb.tsfile.read.common.block.column.Column;

import static com.google.common.base.Preconditions.checkArgument;
import static java.util.Objects.requireNonNull;

/**
 * Used for previous and constant value fill
 */
public class FillOperator implements ProcessOperator {

    private final OperatorContext operatorContext;
    private final IFill[] fillArray;
    private final Operator child;
    private final int outputColumnCount;

    public FillOperator(OperatorContext operatorContext, IFill[] fillArray, Operator child) {
        this.operatorContext = requireNonNull(operatorContext, "operatorContext is null");
        checkArgument(
                fillArray != null && fillArray.length > 0, "fillArray should not be null or empty");
        this.fillArray = fillArray;
        this.child = requireNonNull(child, "child operator is null");
        this.outputColumnCount = fillArray.length;
    }

    @Override
    public OperatorContext getOperatorContext() {
        return operatorContext;
    }

    @Override
    public ListenableFuture<?> isBlocked() {
        return child.isBlocked();
    }

    @Override
    public TsBlock next() {
        TsBlock block = child.nextWithTimer();
        if (block == null) {
            return null;
        }

        checkArgument(
                outputColumnCount == block.getValueColumnCount(),
                "outputColumnCount is not equal to value column count of child operator's TsBlock");

        Column[] valueColumns = new Column[outputColumnCount];

        for (int i = 0; i < outputColumnCount; i++) {
            valueColumns[i] = fillArray[i].fill(block.getColumn(i));
        }

        return TsBlock.wrapBlocksWithoutCopy(
                block.getPositionCount(), block.getTimeColumn(), valueColumns);
    }

    @Override
    public boolean hasNext() {
        return child.hasNextWithTimer();
    }

    @Override
    public void close() throws Exception {
        child.close();
    }

    @Override
    public boolean isFinished() {
        return child.isFinished();
    }

    @Override
    public long calculateMaxPeekMemory() {
        // while doing constant and previous fill, we may need to copy the corresponding column if there
        // exists null values
        // so the max peek memory may be double
        return 2 * child.calculateMaxPeekMemory() + child.calculateRetainedSizeAfterCallingNext();
    }

    @Override
    public long calculateRetainedSizeAfterCallingNext() {
        // we can safely ignore one line cached in IFill
        return child.calculateRetainedSizeAfterCallingNext();
    }

    @Override
    public long calculateMaxReturnSize() {
        return child.calculateMaxReturnSize();
    }
}
